Tube drying apparatus



Oct. 26, 1965 R. M. WILKIE 3,213,479

TUBE DRYING APPARATUS Filed Nov. 20, 1962 "Cu 4s 5' 66 E INVENTOR Robert M. Wi/kie AT'T RNEYS United States Patent 3,213,479 TUBE DRYING APPARATUS Robert M. Willrie, Greenville, Miclr, assiguor to Hupp Corporation, a corporation of Virginia Filed Nov. 20, 1962, Ser. No. 238,863 3 Claims. (Cl. -304) This invention relates to apparatus for drying tubes and more particularly to apparatus for cleaning and drying coils which have been formed from metallic tubing for use as condensers or evaporators of refrigeration apparatus. The interior surface of such coils must be absolutely dry and clean and, since humid air may enter the tube during fabrication, it is necessary to clean and dry the coils after they have been completed.

In the past it has been the practice to heat the coils in ovens for long periods to drive out the moisture, the process often being completed while a vacuum pump was attached to remove moist air from the tube. Since each coil required a long period of heating, the production of a large number of dry coils required much floor space and equipment. The operation has been very expensive and time-consuming tying up a large number of coils between the place of fabrication and the place of assembly into the end product.

The operation of cleaning and drying the interior of the coils can be accomplished at a cost which is substantially below the cost of the prior methods and the operation can be carried on in a floor area which is only a fraction of that formerly required. The time for the operation is reduced from hours to minutes, despite the fact the moisture removal is more nearly complete than with prior methods and apparatus.

It is therefore a primary object of the present invention to provide improved apparatus for cleaning and drying the interior of tubes fabricated as coils expeditiously at low cost with minimum equipment requring little floor space.

The apparatus comprises apparatus for automatically timing and controlling the flow of steam and air and regulating their temperatures as they enter the tubes, thus insuring uniform conditions to perform the cleaning and drying operation most effectively at minimum cost and in the shortest time.

It is therefore a further object of the invention to provide novel apparatus for providing superheated steam and hot dry air at controlled temperatures and to time and control the flow of the steam and air through the coil in a predetermined program.

Further objects and advantages of the invention will be apparent from the following description of a typical embodiment in preferred form, taken in connection with the attached drawing in which:

FIGURE 1 is a semi-diagrammatic view of the apparatus for carrying out the process;

FIGURE 2. is a wiring diagram of the electrical control circuit; and

FIGURE 3 is an elevation, partly in section showing the means for attaching the tube to be cleaned to the conduit which conveys the superheated steam and the hot air to the tube.

As shown in FIGURE 1, saturated steam produced in any suitable steam boiler (not shown) under a pressure of approximately 95 p.s.i. flows through a tube 12 into an insulated pressure vessel 14 where it is heated by an electric resistance heating coil 16 encased in and electrically insulated from a well 18 immersed in the interior space of vessel 14. Coil 16 when energized superheats the steam to a temperature of about 600 F., this temperature being regulated by a thermostat 19 to be described later. A temperature of 600 F. superheats the p.s.i. steam about 250 F. While a wide range of temperatures and pressures can be used successfully in the process, it is desirable that the superheat be at least 200 F.

The superheated steam leaves vessel 14 through a pipe 20 connected to a solenoid or motorized valve 22 which is normally closed but which opens when the valve is energized. When valve 22 is open, the steam will flow into leg 24 of a T 26, then out of stem 28 of T 26, then through a flexible hose 30, a coupling 32 and then through coil 34 to be dried, entering coil 34 through one end 35 which is inserted into coupling 32 as shown in FIGURE 3, and leaving through the opposite end which 15 open to the atmosphere.

Dry air having a dew-point below 60 F. and at a pressure of about p.s.i. is supplied from a storage tank (not shown) through a tube 36 to a pressure vessel 38, where it is heated by an electric resistance coil 40 within an electrically insulated from a well 42, to a temperature of about 400 F. under control of a thermostat 44 as explained below.

The heated dry air leaves vessel 38 through a pipe 46 flowing to a solenoid or motorized valve 48, which is normally closed, but which opens when energized, permitting the air to flow into T 26 through leg 50. From T 26 the air flows through flexible hose 30, coupling 32 and through coil 34.

The steam and air are delivered successively to coil 34 as valves 22 and 48 are successively opened and closed in a manner to be described hereinafter.

Referring to FIGURE 2, electric power is supplied from main lines L1 and L2 through a main power switch 51 to lines 52 and 54.

Thermostats 19 and 44 are commercial thermostats suitable for the temperatures at which they must operate and are connected in series with heating coils 16 and 40 respectively. When the temperature of the steam in vessel 14 is below 600 F., thermostat 19 closes a circuit from line 54 through the thermostat contacts and through heater 16 to line 52 to heat the steam. When the steam temperature reaches 600 F, the circuit is broken at the thermostat contacts.

When the temperature of the air in vessel 38 is below 400 F., thermostat 44 closes a circuit from line 54 through the thermostat contacts, and through heater 40 to line 52 to heat the air in vessel 38. When the air temperature reaches 400 F. the circuit is broken at the thermostat contacts.

An electric motor 60, when energized, rotates three cams 62, 64 and 66 at a speed of about /2 rpm. The time for rotation is adjusted through a suitable adjustable reduction mechanism (not shown) to suit the volume within coil 30. Line 52 is attached to one terminal of motor 60. Line 54 is connected to the other motor terminal through normally-open spring contacts 68, in parallel with which is a normally-open momentary-contact, pushbutton switch 70. When switch 70 is depressed, motor 60 will rotate the cams and as soon as cam 62 has turned so that its raised portion lifts contacts 68, the motor will continue to run even when pushbutton 70 is released, until the cams have made one revolution, when a dwell portion in cam 62 will permit contacts 68 to open, thus stopping the motor when the cams have made one revolution.

A branch circuit is connected from line 52, through the winding of valve 38 and through a pair of normallyopen spring contacts 72 to line 54. When the cams are rotated by motor 60, .a raised portion of cam 64 will close contacts 72, during part of the revolution, thus energizing and opening valve 48, permitting hot air to flow through coil 30. Cam 64 can be shaped to open valve 48 during any part of the cycle desired.

Another branch circuit is connected from line 52 through the winding of valve 22 and through normallyopen spring contacts 74 to line 54. When the cams rotate, a raised portion of cam 66 will close contacts 74 during part of the revolution, thus energizing and opening valve 22, permitting the steam to flow through coil 30, for a period determined by the shape of cam 66.

To clean and dry a coil, the operator merely slips one end 35 of the coil into rubber bushing 76 within coupling 32 as shown in FIGURE 3. Bushing 76 has a small internal taper to suit variations in the diameter of the tube end 35. The operator then depresses button 70 for an instant, whereupon the cams make one revolution, opening valve 22 for a preselected period (normally 90 seconds), then closing valve 22, then opening valve 48 for a preselected period (normally 20 seconds), then closing valve 48 and stopping at the end of the revolution. The operator then removes and caps the ends of coil 30, the entire cleaning operation being automatic.

While there is described and shown herein a preferred form of the invention, the process may be carried out in many other ways all within the scope of the invention as expressed in the appended claims. For example, a springwound timer may be used instead of motor 60, the operator simply winding, the spring to cause the cams 64 and 66 to turn through one revolution. It is also possible to carry on the process by means of manual valves which would replace valves 22 and 48, thus eliminating motor 60, cams 62, 64 and 66 and the associated circuits and contacts. With this construction the operator would control the time of flow of steam and air manually. The preferred form described however has the advantage that the operation is accurately controlled and does not require the attention of a skillful operator.

The invention may be embodied in other specific forms Without departing from the spirit or essential characteristics therefore. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range All of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. Apparatus for drying the interior surfaces of a hollow tube comprising a first insulated pressure-tight container having an inlet through which steam is supplied and a short outlet line leading directly to a fitting adapted to be connected to one end of said tube, means in said container to superheat the steam passing therethrough, a first valve in said outlet line, a second insulated pressure-tight container having an inlet through which air is supplied and a short outlet line leading directly to said fitting, a second valve in said outlet line, means in said second insulated container for heating the air passing therethrough, whereby by manipulation of said valves said superheated steam and said hot air may be delivered sequentially through said tube to thereby dry said tube.

2. The apparatus according to claim 1 together with means for automatically maintaining the interiors of said containers at predetermined temperatures.

3. The apparatus according to claim 1 together with means for automatically sequentially opening and closing said first valve annd thereafter opening and closing said second valve.

References Cited by the Examiner UNITED STATES PATENTS 983,548 2/11 Gale. 1,573,070 2/26 Johnson et a1 15304 2,023,496 12/35 Todd 134-22 2,289,351 7/42 Dixon et a1. 2,549,809 4/51 Heineman 34-104 X 2,550,683 5/51 Fletcher et al 122-479 X 2,597,896 5/152 Oster 13422 2,674,760 4/54 Finch 15-304 FOREIGN PATENTS 542,377 4/56 Italy.

WALTER A. SCHEEL, Primary Examiner.

CHARLES A. WILLMUTH, Examiner. 

1. APPARATUS FOR DRYING THE INTERIOR SURFACES OF A HOLLOW TUBE COMPRISING A FIRST INSULATED PRESSURE-TIGHT CONTAINER HAVING AN INLET THROUGH WHICH STEAM IS SUPPLIED AND A SHORT OUTLET LINE LEADING DIRECTLY TO A FITTING ADAPTED TO BE CONNECTED TO ONE END OF SAID TUBE, MEANS IN SAID CONTAINER TO SUPERHEAT THE STEAM PASSING THERETHROUGH, A FIRST VALVE IN SAID OUTLET LINE, A SECOND INSULATED PRESSURE-TIGHT CONTAINER HAVING AN INLET THROUGH WHICH AIR IS SUPPLIED AND A SHORT OUTLET LINE LEADING DIRECTLY TO SAID FITTING, A SECOND VALVE IN SAID OUTLET LINE, MEANS IN SAID SECOND INSULATED CONTAINER FOR HEATING THE AIR PASSING THERETHROUGH, WHEREBY BY MANIPULATION OF SAID VALVES SAID SUPERHEATED STEAM AND SAID HOT AIR MAY BE DELIVERED SEQUENTIALLY THROUGH SAID TUBE TO THEREBY DRY SAID TUBE. 